It is well known that healthy social relationships foster mental and physical health. Unfortunately, some people find relationships overwhelming and cope in self-defeating ways, extreme forms of which are captured in Borderline (BPD) and Avoidant (APD) Personality Disorders. BPD is characterized by volatile relationships involving angry, impulsive and self-injurious reactions to the threat of rejection. APD is characterized by pervasive and self-undermining avoidance of situations and roles entailing potential exposure to rejection. Our goal is to advance knowledge of processes that generate these debilitating disorders by building on basic personality research on two social-cognitive dispositions: (1) Rejection sensitivity (RS) is the disposition to anxiously expect, readily perceive, and intensely react to rejection. (2) Self-regulatory competency is the ability to effortfully override automatic reactions in favor of less dominant but more appropriate responses. Prior work shows that, in people high in RS, rejection cues rapidly and automatically prepare them to detect and to react intensely to forestall rejection. This potentially adaptive threat-response system can become maladaptive if activated indiscriminately in situations that require reflective, strategic behavior or when the threat is minimal. While both BPD and APD involve high RS, BPD alone is characterized by the dysregulating consequences of managing an intense need for social connection along with an intense fear of rejection. The proposed research examines how RS and regulatory competency interact to influence social threat processing dynamics and psychiatric symptoms in these disorders. Persons with BPD (n = 50) and APD (n = 50) recruited from the community and assessed with diagnostic interviews will be compared with two groups without personality disorders -- one group with Major Depression and one with no disorders. The research involves a unique combination of (a) experimental laboratory paradigms that enable fine-grained analyses of if & then processes underlying BPD and APD symptoms, and (b) a 21-day experience-sampling diary that will show how these processes relate to psychiatric symptoms in daily life. Aim 1 is to assess whether individuals with BPD or APD selectively attend to, perceive, and react to social cues in ways that reflect high RS. Aim 2 is to assess aspects of regulatory competency relevant to APD and BPD and to determine how they protect against the personal and interpersonal difficulties generated by RS. Borderline (BPD) and Avoidant (APD) Personality Disorders are serious disorders associated with severe functional impairment, and in the case of BPD, self-injurious urges and impulsive behaviors that often incur very high healthcare costs. By clarifying the specific processes by which the debilitating symptoms of these disorders emerge, this research will improve assessment procedures and provide a foundation for scientifically justified interventions intended to reduce the toll of these disorders on individuals and society. [unreadable] [unreadable] [unreadable]